Nutplate for fluid filter

ABSTRACT

A unitary nutplate for a fluid filter assembly provides a threaded mounting interface between an engine block mounting base and the remainder of the fluid filter assembly. The unitary nutplate is designed with an enlarged inside diameter in order to reduce the moment arm between the outer shell of the fluid filter assembly and the filtering element. With the enlarged inside diameter, the annular sidewall of the unitary nutplate does not include any flow passageways for the entering fluid and accordingly other flow passageways are created. In one arrangement, the nutplate has a generally cylindrical lower wall which cooperates with an inner seal which is designed with fluid flow passageways. In an alternate nutplate design, depending projections from the lower edge of the nutplate provide a series of flow passageways therebetween and the cooperating inner seal does not include flow passageways.

BACKGROUND OF THE INVENTION

The present invention relates in general to the design of a fluid filterwhich includes a stamped steel nutplate for threaded attachment to afilter head. More specifically, the present invention relates to a fluidfilter design wherein the nutplate has a threaded aperture which islarger, compared to earlier designs, in order to provide a reducedmoment arm. Included in the disclosed design of the present inventionare novel inner and outer seals which provide improved performancecharacteristics. The anticipated use for the present invention is incooperation with a vehicle engine such as a diesel engine.

A related embodiment of the present invention is directed to the spin-onfilter and the filter head interface. More specifically, this relatedembodiment includes a design relationship for the specific sequence ofthread and seal (inner and outer) engagements between the fluid filterand the filter head in order to facilitate easier installation.

While the design of fluid filters over the years has involved literallyhundreds of different concepts, the basic principles of operation haveremained much the same. The fluid substance to be filtered must first beintroduced into the filter housing or shell and from there directed toflow into and through the filtering media. As the filtered fluid exitsfrom the filtering media, it needs to be routed to a flow outlet.Throughout this flow loop, it is generally preferred that the unfilteredfluid not by-pass the filtering media and that fluid not leak from thefilter shell. While these functions can normally be achieved by the useof properly designed and positioned seals, over time seals deteriorateand leakage can occur. The passage of time and continued use can alsocause deterioration of other components and interfaces within the fluidfilter. For example, each pulse of fluid pressure creates a variableload on the nutplate causing it to flex. The flexing of the nutplatecreates wear in the plate and weakens nutplate interfaces anddeterioration begins. In particular, the flexing causes the outer sealto deflect which in turn can create a leakage interface. To some extentthe rate of deterioration is affected by the operating environment andthe nature of the substance being filtered. If a longer service intervalis desired for the filter assembly, it is important to be able to slowthe rate of deterioration.

In order to provide a representative sampling of earlier fluid filterassembly designs, the following listed patents should be considered:

    ______________________________________    PATENT NO.    PATENTEE      ISSUE DATE    ______________________________________    4,841,628     Nagle         Jun. 27, 1989    4,839,037     Bertelsen et al.                                Jun. 13, 1989    4,855,047     Firth         Aug. 8, 1989    5,118,417     Deibel        Jun. 2, 1992    5,548,893     Koelfgen      Aug. 27, 1996    4,992,166     Lowsky et al. Feb. 12, 1991    5,171,430     Beach et al.  Dec. 15, 1992    5,395,518     Gulsvig       Mar. 7, 1995    4,052,307     Humbert, Jr.  Oct. 4, 1977    1,033,858     Adams         Jul. 30, 1912    2,646,886     Le Clair      Jul. 28, 1953    2,743,019     Kovacs        Apr. 24, 1956    3,859,216     Sisson et al. Jan. 7, 1975    5,300,223     Wright        Apr. 5, 1994    5,445,734     Chen          Aug. 29, 1995    1,647,799     Hammer        Nov. 1, 1927    ______________________________________

In those diesel engine filter designs which employ an internallythreaded nutplate, one of the design concerns is the type and level ofvibration which the filter assembly sees in its actual use environment.In a typical installation, the fluid filter assembly is threadedlyattached to a mounting base or filter head. The filter head typicallyprovides the flow passages for the incoming (unfiltered) fluid as wellas a flow passage for the exiting (filtered) fluid. An externallythreaded, hollow stem is typically used in order to threadedly mate withan internally threaded aperture in the nutplate. Since the threaded stemis hollow, it is constructed and arranged to function as an exit flowpassage or conduit.

Vibrations due to engine operation and those coming from road conditionsare transmitted to the fluid filter assembly by means of the filtermounting base and the threaded stem. The distance from the outsidediameter of the threaded stem to the filter housing (i.e., shell)defines a moment arm about which the filter assembly is able to move.The greater the length of the moment arm, the greater the amplitude ofthe transmitted vibrations and the greater the rate of deterioration ofthe seals of the fluid filter assembly and in turn the greater the rateof deterioration of the filter assembly. Vibrations of the typedescribed also have a deterioration effect on the seals, the nutplateand other structural components of the fluid filter. In order toincrease the useful life of the fluid filter assembly, it would bedesirable to reduce the length of the moment arm. This is accomplishedby the present invention by increasing the size of the internallythreaded aperture in the nutplate and in turn by providing aninternally-threaded mounting portion with an increased outside diameter.

By employing a nutplate with the same outside diameter, an increase inthe inside diameter size reduces the radial thickness or width of thenutplate sidewall and in turn reduces the available area which can beused for drilling, molding, or otherwise incorporating fluid flow holes.The inside and outside diameters of the nutplate define the sidewallwhich has an annular ring shape. While flow holes could conceivably beprovided in this annular ring area, each flow hole would, by necessity,have to be quite small. In order to have enough flow area for adequateand efficient flow through the fluid filter, a relatively large numberof these smaller holes is required. As the number of holes increases,the spacing between holes decreases and this would significantly weakenthe nutplate. Consequently, a modified design needs to be provided forthe nutplate and for the cooperating filter seals in order to providefor the necessary flow of unfiltered fluid into the fluid filterassembly. These modified designs are provided by the present inventionin a novel and unobvious manner. As will be described, there are fourdifferent inner seals disclosed in order to cooperate with the variousnutplate embodiments of the present invention.

The nutplate designs of the present invention are disclosed in variousarrangements and for each one there is a specifically styled inner seal.Each inner seal design is positioned over the end of the filteringelement and around an exit flow conduit which is part of the engineblock mounting base. One style of inner seal cooperates with one styleof nutplate of the primary embodiment in order to create flowpassageways therebetween through alternating open sections in the seal.In the other style of inner seal, the flow passageways which are definedbetween the nutplate and the inner seal are created by the use ofdepending projections from the lower wall of the nutplate. Otherwise,the two inner seals function in a similar fashion. In the relatedembodiment of the fluid filter, one style of inner seal cooperates withthe mounting base and radial flow areas are created between the nutplateand the filter element. The other style of inner seal for this relatedembodiment includes its own flow passageways as well as cooperating withthe nutplate for the creation of radial flow areas.

The outer seal provides a sealed interface between the mounting base andthe outer shell which is formed over the upper annular portion of thenutplate, outward of the location of the threaded connection. The outerseal is uniquely styled with a pair of circumferential ribs for sealingredundancy. The outer seal also helps to dampen vibrations which may betransmitted by the mounting base. The cooperation of the inner and outerseals with the nutplate styles of the present invention provides animproved fluid filter assembly.

SUMMARY OF THE INVENTION

A seal arrangement for a fluid filter assembly which is constructed andarranged to threadedly mount onto an engine block mounting baseaccording to one embodiment of the present invention comprises an innerseal and an outer seal. The fluid filter assembly includes an outershell, a filtering element located within the outer shell and definingtherewith an annular clearance space and a nutplate which is anchored tothe outer shell and which provides a threaded interface for assembly tothe engine block mounting base. The inner seal is positioned between thenutplate and the filtering element. The outer seal is positioned betweenthe engine block mounting base and the nutplate. Further, the outer sealincludes a pair of spaced-apart ribs which provides a sealing interfaceagainst the engine block mounting base. The inner seal cooperates withthe nutplate to provide a plurality of flow paths between the inner sealand the nutplate between the engine block mounting base and the annularclearance space.

One object of the present invention is to provide an improved sealarrangement for a fluid filter assembly.

Related objects and advantages of the present invention will be apparentfrom the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view in full section of a fluid filterassembly according to a typical embodiment of the present invention.

FIG. 2 is a front elevational view in full section of the FIG. 1 fluidfilter assembly as mounted on an engine block mounting base according tothe present invention.

FIG. 3 is a top plan view of the FIG. 2 engine block mounting base withthe FIG. 1 fluid filter assembly attached.

FIG. 4 is a front elevational view of a unitary nutplate according to atypical embodiment of the present invention.

FIG. 5 is a front elevational view in full section of the FIG. 4nutplate.

FIG. 6 is a perspective view of an inner seal which comprises oneportion of the FIG. 1 fluid filter assembly.

FIG. 7 is a front elevational view in full section of the FIG. 6 innerseal.

FIG. 8 is a bottom plan view of an outer seal which comprises oneportion of the FIG. 1 filter assembly.

FIG. 9 is a front elevational view in full section of the FIG. 8 outerseal.

FIG. 10 is an enlarged, partial, front elevational view of the sidewallof the FIG. 8 outer seal.

FIG. 11 is a front elevational view in full section of an alternativefluid filter assembly according to another embodiment of the presentinvention.

FIG. 12 is a front elevational view in full section of the FIG. 11 fluidfilter assembly as assembled onto an engine block mounting base.

FIG. 13 is a top plan view of the FIG. 12 engine block mounting basewith the FIG. 11 fluid filter assembly attached.

FIG. 14 is a front elevational view of a nutplate which comprises oneportion of the FIG. 11 fluid filter assembly.

FIG. 15 is a front elevational view in full section of the FIG. 14nutplate.

FIG. 16 is a perspective view of an inner seal which comprises oneportion of the FIG. 11 fluid filter assembly.

FIG. 17 is a front elevational view in full section of the FIG. 16 innerseal.

FIG. 18 is a partial front elevational view in full section of a fluidfilter according to another embodiment of the present invention.

FIG. 19 is a front elevational view in full section of a filter head towhich the FIG. 18 fluid filter is assembled according to the presentinvention.

FIG. 20 is a partial, front elevational view in full section of the FIG.18 fluid filter as assembled onto the FIG. 19 filter head according tothe present invention.

FIG. 21 is a front elevational view in full section of the FIG. 20partial view.

FIG. 22 is a perspective view of an inner seal comprising one portion ofthe FIG. 18 fluid filter.

FIG. 23 is a front elevational view in full section of the FIG. 22 innerseal.

FIG. 24 is a perspective view of the underside of the FIG. 19 filterhead according to the present invention.

FIG. 25 is a partial front elevational view in full section of a fluidfilter according to another embodiment of the present invention.

FIG. 26 is a front elevational view in full section of a filter head towhich the FIG. 25 fluid filter is assembled according to the presentinvention.

FIG. 27 is a partial, front elevational view in full section of the FIG.25 fluid filter as assembled onto the FIG. 26 filter head according tothe present invention.

FIG. 28 is a front elevational view in full section of the FIG. 27partial view.

FIG. 29 is a perspective view of an inner seal comprising one portion ofthe FIG. 25 fluid filter.

FIG. 30 is a front elevational view in full section of the FIG. 29 innerseal.

FIG. 31 is a perspective view of the underside of the FIG. 26 filterhead according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiment illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Referring to FIGS. 1, 2, and 3, a fluid filter assembly 20 which isconstructed and arranged according to the present invention isillustrated. In FIG. 1 the filter assembly 20 is illustrated as it wouldappear unmounted onto the filter head 21 (engine block mounting base) ofFIG. 2. In the FIG. 2 illustration, the filter assembly 20 is threadedlyattached and mounted onto filter head 21. FIG. 3 is a top plan (end)view of the filter head 21 with the filter assembly 20 attached.

Filter assembly 20 includes a full-flow, primary filter element 24, acooperating by-pass filter element 25, an outlet flow nozzle 26, anouter shell 27, a support spring 28, an inner seal 29, a unitarynutplate 30, and an outer seal 31. The primary filter element 24includes a hollow interior 35, a lower endplate 36, and an upperendplate 37. The two endplates are sealed across their correspondingprimary filter element ends in order to prevent fluid flow out throughthe ends of the primary filter element 24. The by-pass filter element 25abuts up against the lower endplate 36 and includes an enclosing baseendplate 38. The interior of endplate 36 is open and formed with short,cylindrical conduit 36a. Tube 39 which fits around conduit 36a providesfluid flow communication from by-pass filter element 25 into nozzle 26.In the preferred embodiment, tube 39 is in unitary combination with flownozzle 26, (i.e., a one-piece combination). The unitary tube 39 and flownozzle 26 is constructed out of nylon. It is also envisioned that aseparate tube 39 can be used and fitted around conduit 36a and locatedwithin nozzle 26.

Upper endplate 37 is formed with an inner annular lip 44 which providesan anchoring edge for inner seal 29. Inner seal 29 is fabricated out ofrubber. The outwardly flared end 45 of flow nozzle 26 fits around theinner annular lip 44. The inside annular surface 46 of inner seal 29fits up against stem 47 of the filter head 21 (see FIG. 2). The unitarynutplate 30, which may be stamped, molded, or machined, is internallythreaded and is assembled to the externally-threaded portion 48 offilter head 21. In the preferred embodiment nutplate 30 is stamped outof metal.

The outer shell 27 is metal and has a substantially cylindrical sidewall49 which includes a formed upper lip 50 which is shaped with an invertedreceiving channel 51. Tightly and securely anchored into annular channel51 is the annular upper, outer lip 52 of nutplate 30. While it would bedesirable for this interface junction to be liquid-tight by themechanical fit of the components, this is not achievable. Accordinglythe outer seal 31 is provided to ensure that there is no leakage throughthis interface. Outer seal 31 is fabricated out of rubber. While anadhesive may be placed between the annular channel 51 and lip 52 ofnutplate 30, this is done to help keep the nutplate from spinning duringinstallation. Outer seal 31 provides an additional level of securityagainst fluid leakage. Annular seal 31 fits down inside of the innerwall 56 of channel 51 and extends upwardly and outwardly over upper wall57 of channel 51. The upper surface 58 of seal 31 abuts up tightlyagainst the base 59 of channel 60 of filter head 21.

The end face 63 of filter head 21 includes an alternating pattern offour bolt holes 64 and four fluid inlet apertures 65. The fluid inletapertures 65 provide fluid inlets for the fluid to be filtered to flowinto the filter head 21. The four bolt holes 64 provide a means ofmounting the filter head 21 to the vehicle engine. The open interior ofhead 21 provides a flow path into the vicinity of inner seal 29 wherethe unfiltered fluid is able to flow in a radially outward directionbeneath the lower edge of nutplate 30. Stem 47 is hollow and issubstantially coaxial with nozzle 26. The hollow interior 47a creates aflow exit passageway for the filtered fluid exiting from the primaryfilter element 24 and from the by-pass filtering element 25.

As will be understood by reference to FIGS. 2, 6, and 7, the inner seal29 is configured with four flanges 65a-65d and in alternating sequencetherewith, four flow openings 66a-66d. Depending on the threaded depthof the filter head 21 as it is axially advanced into the nutplate 30,either the lower edge of the filter head (portion 48) or the lower edgeof nutplate 30 may come to rest on the top surface of seal 29. Onceeither the filter head or nutplate (or conceivably both) comes to reston the top surface of the seal, four fluid flow passages are createdpast the inner seal via the four flow openings 66a-66d. These flowpassages lead to outer annular clearance space 67 and from this spacethe fluid flows into the primary filter element 24 and as appropriate,into the by-pass filter element 25. Clearance space 67 is created anddefined by the cylindrical shape of the outer shell 27, and by thecylindrical shape of filtering elements 24 and 25.

Referring now to FIGS. 4 and 5, the nutplate 30 is illustrated ingreater detail. Nutplate 30 is an annular member with aninternally-threaded lower wall portion 70 an annular upper wall portion30a and an annular connecting portion 30b. Two radiused separate thethree wall portions, and an annular outer lip 52 is located at the upperedge of wall portion 30a. As previously described, the lower edge 73which is a continuous cylinder in shape seals against the top surface ofthe inner seal 29. The outer lip 52 is securely received within theinverted receiving channel 51 of the outer shell. The slight undercutedge 74 on lip 52 is able to be used to crimp the outer shell 27 intorecess 75 beneath edge 74 for a tighter and more secure joint betweenthe outer shell 27 and the nutplate 30. In contrast to the typicaldesigns for molded nutplates, internally-threaded portion 70 issubstantially larger than earlier designs such that the radial distancebetween the inside diameter surface 70a of cylindrical wall 70 and theoutside diameter of outer lip 52 is relatively short, therebysignificantly reducing the length of the moment arm. In one embodimentof the present invention, the inside diameter size of portion 70 isapproximately 3.52 inches and the outside diameter size of lip 52 isapproximately 4.43 inches for a moment arm of approximately 0.455inches. With the moment arm reduced to a significantly shorter length,the amplitude of the vibrations seen by the filter assembly 20 isreduced. Vibrations are generated by engine operation and aretransmitted to the vehicle as the vehicle travels over the road. Thesevibrations are transmitted to the fluid filter assembly by the filterhead 21 at the location of the threaded fit between nutplate portion 70and the threaded portion 48 of filter head 21. The transmittedvibrations travel to the outer shell 27 and it is believed that thelength of the moment arm is directly proportional to the amplitude ofthe vibrations as seen by the outer shell. By increasing the insidediameter size of portion 70 over that of the more "traditional"nutplates for approximately the same outer shell size, the moment arm isreduced which in turn reduces the amplitude of the vibrations which aretransmitted to and seen by the outer shell.

With "traditional" nutplates, fluid inlet apertures are formed in thatportion of the nutplate between the threaded inside diameter and theouter peripheral edge. Since the inside diameter of traditionalnutplates is substantially smaller than the inside diameter of thepresent invention nutplate, there is sufficient area which is of anannular ring shape for fluid inlet apertures to be molded, cast, ormachined directly into and through the nutplate. However, with thepresent nutplate design, the total width of the sidewall from the insidediameter 70a to the outside diameter of outer lip 52 is very narrow,typically less than 1/2 inch. The only land area for inlet flow holes tobe formed is between radius bends 71 and 72. The narrow width of theland area means that any flow hole which would be drilled, cast, ormolded through that area must be extremely small. In order to getadequate fluid flow, a large number of these smaller flow holes would berequired. In order to get sufficient flow area, a great deal of nutplatematerial would have to be removed from this narrow land area and thiswould substantially weaken the nutplate. Accordingly, the nutplate ofthe present invention is free of any flow inlet holes which are actuallyformed into and through any portion of the nutplate 30. Instead, thepresent invention incorporates a unique style of nutplate in combinationwith a cooperating inner seal in order to create a plurality of flowpaths for the incoming unfiltered fluid which actually passes betweenthe nutplate and the corresponding inner seal as it flows from theengine block mounting base into the annular clearance space 67.

Filter head 21 includes threaded portion 48 which provides the mountingor attachment structure for the fluid filter assembly 20. With thefilter head 21 properly mounted to the engine and with the flow passagesand conduits connected, the filter assembly 20 can be readily and easilyinstalled by threading the nutplate 30 onto portion 48. As this threadedengagement is advanced and tightened, the outer annular seal 31 is drawninto sealing contact against the upper wall 57 and the inner wall 56 ofchannel 51.

Referring now to FIGS. 6 and 7, the unitary inner seal 29 is illustratedin greater detail. Each of the four flanges 65a-65d are virtuallyidentical and are configured so as to be symmetrical about acorresponding and radiating centerline. Centerlines 78a-78d are located90 degrees apart. Equally-spaced between adjacent flanges 65a-65d areflow openings 66a-66d. Fluid flow entering filter head 21 is initiallyreceived between stem 47 and threaded portion 48. In order to travelinto annular clearance space 67, the fluid must travel radiallyoutwardly beneath the lower edge 73 of nutplate 30. The only placeswhere such fluid flow can occur is at the locations of the four flowopenings 66a-66d.

Each flange 65a-65d includes a radiused outer lip 82 and a land area 83.The lower edge 73 of nutplate 30 rests inside of the four lips 82 and ontop of the four land areas 83. The center hub 84 is a hollow, annularstructure which includes inside annular surface 46 with two spaced-apartannular ribs 85 and 86. These two ribs tightly abut up against stem 47in order to provide a sealed interface. The outer surface 93 of centerportion 84 includes two spaced-apart sealing ribs 94 and 95 which fittightly up against the annular lip 44 of upper endplate 37. Each flange65a-65d is illustrated with an optional depending wall 87 which includesan offset portion 88. Since the preferred embodiment of each flange doesnot include the depending wall nor the offset portion, these areillustrated in broken line form. If present as an alternativeembodiment, the tapered and offset portion 88 is constructed andarranged to fit beneath inner annular lip 44. In this alternativeembodiment, using the optional wall 87, the innermost edge of lip 44fits within recess channel 92.

The inner seal 29 is designed to provide dual radial seals on theupstream side of the fluid flow as well as on the downstream side. Thetwo ribs 85 and 86 on the inside surface 46 of center portion 84 abut upagainst stem 47 to prevent the incoming fluid flow from by-passing thefilter elements by passing directly into flow nozzle 26. On thedownstream side the filtered fluid in nozzle 26 is precluded fromflowing past center portion 84, on either the inside diameter side or onthe outside diameter side due to the presence of ribs 85 and 86 and ribs94 and 95, respectively.

In contrast to earlier seal designs which provide sealing by means of acompression face seal, the present invention incorporates dual radialseals. The inner seal 29 also functions as a vibration damper betweenthe nutplate 30 and the upper endplate 37 to limit the level ofvibration which is transmitted to the primary filter element 24. Duringthe installation of the filter assembly 20 onto filter head 21, thepositioning of stem 47 into center portion 84 provides some degree ofcoarse alignment between the filter assembly 20 and the filter head 21,such that the threaded engagement can be achieved more easily,especially in blind installations.

Referring now to FIGS. 8, 9, and 10, the outer seal 31 is illustrated ingreater detail. Outer seal 31 is a substantially annular member with asubstantially cylindrical sidewall portion 98 which is bounded on thetop by upper surface 58 and radial flange 99 and on the bottom by radiallip 100. Upper surface 58 includes two raised annular ribs 101 and 102which are radially spaced apart from each other by an annular recessedportion 103. Portion 103 is curved in lateral section as is illustratedin FIG. 10. The outer surface 104 of flange 99 is substantiallycylindrical and underside surface 105 is substantially planar. Thecylindrical axis of surface 104 is substantially perpendicular tosurface 105. The upper annular surface 106 of lip 100 is substantiallyplanar and substantially parallel to surface 105. The outer cylindricalsurface 107 of sidewall portion 98 is substantially concentric withrespect to surface 104.

The lower surface 110 has an annular ring shape and is substantiallyplanar. The geometric planes which generally define and are coextensivewith surfaces 110, 106, and 105 are each substantially parallel to theothers. Surfaces 105 and 107 fit tightly up against upper wall 57 andinner wall 56, respectively, of the inverted receiving channel 51. Theabutment of these two surfaces to the two cooperating walls establishesa fluid-tight interface between outer seal 31 and the formed upper lip50 of outer shell 27 which defines channel 51.

While it has been described that the upper surface 58 abuts up tightlyagainst base 59 of channel 60, it is actually ribs 101 and 102 whichcontact base 59. Rib 101 extends above surface 111 by approximately0.033 inches and rib 102 extends above surface 11 by approximately 0.039inches. The slight height difference between these two ribs is designedinto the upper seal in order to provide enhanced sealing and to createsealing redundancy. Seal 31 provides a means of preventing any fluidleakage from the filter assembly 20 between the filter assembly and thefilter head 21. Additionally, seal 31 provides a damper againstvibration. While most outer seals of earlier fluid filter assembliesprovide a single seal by means of a compression face seal, the presentinvention, by way of seal 31, uses the two ribs in compression. Thebuilt in redundancy of the two ribs offers first and second lines ofdefense to prevent filter assembly leakage. If there is a deteriorationof the seal through one of the ribs such that the seal opens, the secondrib provides a backup seal to prevent leakage. By using the two ribs 101and 102, any slight dimensional variations or misalignments will notpreclude the establishment of a sealed interface. As the two ribs aregradually compressed, the resistance force of seal 31 against furthercompression also increases rapidly. This gives a positive feedback infeel to the installer so that the installer can tell where to stopwithout overtightening (i.e., threading) the filter assembly 20 into thefilter head 21. In order to maintain the flexibility and resiliency ofseal 31, it is important that is not be compressed to the point that theseal becomes functionally "solid".

By creating seal 31 such that rib 102 is "higher" than rib 101 byapproximately 0.006 inch, seal 31 will not move from its position nortip over during installation. Further, the protruding tips of each ribs101 and 102 have less total surface area, even when compressed, thanearlier conventional face seal designs. This reduced surface areareduces the installation and removal friction and torque, making thefilter assembly easier for the customer to use. Radial lip 100 andsurface 106 are constructed and arranged to catch onto the lower edge ofthe inner wall 56 of channel 51.

While radial lip 100 is substantially annular in shape, it is configuredin a split ring fashion as is illustrated in FIG. 8. Lip 100 includesfour circumferential sections 113, 114, 115, and 116. Each pair ofadjacent sections are spaced apart by spaces 117, 118, 119, and 120. Asdescribed, lip 100 is used to snap beneath the inner, lower edge 121 ofinner wall 56 and thereby anchor the outer seal 31 to the remainder offilter assembly 20. In this way, the seal 31 comes off with the filterassembly 20 when the filter assembly 20 is removed from the filter head21, rather than staying on the filter head 21. The split-finger designof radial lip 100 (i.e., the four spaced-apart sections 113-116) enablesan easy snap-fit assembly of the outer seal 31 and permits a simplifiedmolding process.

Referring now to FIGS. 11, 12, and 13, an alternative filter assembly130 according to the present invention is illustrated. Fluid filterassembly 130 is virtually identical to fluid filter assembly 20 with twoexceptions. Fluid filter 130, as compared to fluid filter assembly 20,includes a differently styled nutplate 131 (see FIGS. 14 and 15) and adifferently styled inner seal 132 (see FIGS. 16 and 17). The filter head21 of FIGS. 12 and 13 is the same as that used in the filter assemblyand filter head combination of FIGS. 2 and 3. The remainder of filterassembly 130 is the same as filter assembly 20 and the outer seal 31 ofFIGS. 11 and 12 is identical to the outer seal 31 of FIGS. 1 and 2.

With regard to the only two differences between filter assembly 130 andfilter assembly 20, refer to FIGS. 14-17. In FIGS. 14 and 15, annularnutplate 131 is illustrated in greater detail. Nutplate 131 is the sameas nutplate 30 from bend 71 to outer lip 52. Below bend 71 the twonutplate designs are different. While nutplate 30 has aninternally-threaded portion 70 which is substantially cylindrical, theinternally-threaded portion 135 of nutplate 131 is configured with asmaller cylindrical section 136 and three depending projections 137. Thethree projections 137 are equally spaced around the circumference ofsection 136 and extend downwardly from lower edge 138. A consequence ofthis design is the creation of three flow openings 139, 140, and 141. Inorder to help visualize the nature of the three flow openings 139-141,imagine a horizontal line drawn in FIGS. 14 and 15 which touches thelower edge of each projection 137. This horizontal line creates threeopenings, each of which is defined on its boundary side by lower edge138, on its sides by one pair of adjacent projections 137, and on itslower boundary by the imaginary horizontal line. In the actual design ofthe present invention, the imaginary horizontal line is in fact replacedby the upper or top surface of inner seal 132. The combination ofnutplate 131 and inner seal 132 creates and defines the three flowopenings 139-141 between these two members and through which unfilteredfluid passes on its way from the engine block mounting base to theannular clearance space 67. In this arrangement the entering flow ispast the nutplate 131 and across the surface of the inner seal 132. Inthe FIG. 1 arrangement the entering flow is beneath (i.e., across) thenutplate lower edge 73 and past adjacent flanges 65a-65d. The nutplate131 is constructed and arranged such that the lower surface of eachprojection rests on the upper surface of inner seal 132. The insidesurface of each projection is internally threaded as a continuation ofthe thread pitch present as part of section 136. In this way, thethreaded advancement of the filter assembly 130 by way of nutplate 131onto filter head 21 does not have to stop at the lower edge 138.

Referring now to FIGS. 16 and 17, the inner seal 132 is illustrated ingreater detail. Seal 132 is virtually identical to inner seal 29 exceptthat the four flanges 65a-65d are replaced by a continuous annular ringportion 143. Since the four openings 66a-66d are effectively "filled-in"by the design of seal 132, an alternative fluid flow path needs to beestablished. Since the fluid cannot flow through the inner seal 132, thefluid must flow across the upper surface 144 of seal 132. This is wherethe openings 139-141 are utilized. The fluid is able to flow beneathlower edge 138, through openings 139-141, and into clearance space 67.The center portion 145 and all of the corresponding and cooperatingstructural features are identical to center portion 84 and itscorresponding and cooperating structural features. The circumferentiallyarranged series of equally-spaced pockets 146 which are formed in theupper or top surface 144 of seal 132 are provided for weight andmaterial reduction. The nature of use for the inner seal 132 and itsplacement within the filter assembly permits a weight and materialreduction without creating any negative effect, such as reducing thestrength or rigidity of the part. A reduction in the amount of materialhelps to lower the cost of the fluid filter assembly. The placement ofthe inner seal 132 flat against the filter endplate 37 provides thenecessary backing to the inner seal 132 and the sealing capabilities ofthe inner seal are not affected by the creation of the weight-reduction,material-reduction pockets 146.

A related embodiment of the present invention is illustrated in FIGS.18-31. FIG. 18-24 illustrate one style of this related embodiment whileFIGS. 25-31 illustrate a second style of this related embodiment. Thefocus of this related embodiment is on the installation procedure andthe sequence of steps involving the threading of the fluid filter 160onto the cooperating filter head 161 (see FIGS. 18-21). In thedescription which follows, references to upper and lower and top orbottom are based upon the orientation of the fluid filter 160 and filterhead 161 as illustrated in FIGS. 18-21. However, it is to be understoodthat in actual vehicles the orientation of these two components could bedifferent from that illustrated herein.

Referring now to FIG. 18, the open end of a fluid filter 160 accordingto the present invention is illustrated. The remainder of fluid filter160 is illustrated in FIG. 21. A cooperating filter head 161 isillustrated in FIG. 19. The assembly (i.e., installation) of fluidfilter 160 and filter head 161 are illustrated in FIGS. 20 and 21.

Fluid filter 160 includes an outer housing 162, annular nutplate 163, aprimary filtering element 164, a by-pass filtering element 165, an innerseal 166, an outer seal 167, and a support spring 168. The annularnutplate 163 is a unitary member which is internally threaded forthreaded engagement and assembly to the externally threaded annular wallof the filter head. The primary filtering element 164 includes a hollow,generally cylindrical filtering media and top and bottom endplates, 169and 170, respectively. The by-pass filtering element 165 includes alower endplate 174 which seats against the upper end 175 of supportspring 168. The opposite end of by-pass filtering element 165 is sealedup against the bottom endplate 170 and annular inner plate 176 closesoff the remainder of the by-pass filtering element 165. All exitingfluid must pass through outlet conduit 177.

Venturi flow nozzle 180 is a unitary member which includes a lowpressure zone 181 at the throat and a gradually diverging sidewall 182which has a conical shape and defines a pressure-recovery zone 183 inthe downstream divergent section 184. The flow nozzle 180 is effectivelypositioned entirely within the hollow interior 185 of the primaryelement. One end of tube 186 fits over conduit 177 in a liquid-tightmanner and the opposite end 187 of the tube is positioned within the lowpressure zone 181 and is substantially centered within the definingsidewall of the flow nozzle. In the preferred embodiment the tube 186and flow nozzle 180 are combined as a unitary member.

Fluid filter assembly 20 and fluid filter 160 are virtually identicalrelative to the design and arrangement of the outer housing or shell,the two filtering elements, the venturi flow nozzle, and connectingtube, endplates, and the support spring. This portion of the presentinvention which is not the primary focus of the invention is alsodescribed in part in U.S. Ser. No. 08/699,713, filed Aug. 27, 1996,claiming priority to U.S. Ser. No. 08/084,875, filed Jun. 30, 1993. Thepending Ser. No. 08/699,713 patent application is hereby expresslyincorporated by reference for its disclosure of the flow mechanics andthe cooperating structures associated with the two filtering elements.

The relationship of the outer shell 27 to the nutplate 30 and outer seal31 as illustrated in FIG. 1 and described is the same for outer housing162, nutplate 163, and outer seal 167 as illustrated in FIGS. 18, 20,and 21. Further, outer seal 31 and outer seal 167 are virtuallyidentical to each other in size, shape, material, and function. Theprimary differences between the FIG. 1 fluid filter assembly 20 and theFIG. 21 fluid filter 160 involve the nutplates 30 and 163 and the innerseals 29 and 166. The FIG. 21 embodiment also establishes an importantand unique assembly relationship between the fluid filter 160 and thefilter head 161. This important and unique assembly relationship isutilized in order to improve the installation procedure of the fluidfilter 160 onto the filter head 161 as well as to improve the procedurefor removal of the fluid filter 160 from the filter head 161.

Inner seal 166 is positioned between the top endplate 169 and the loweredge 190 of the unitary nutplate 163. An inner lip portion 191 of theinner seal 166 extends inwardly in a radial direction and defines asubstantially cylindrical passageway 191a for receipt of the protrusion192 of the inner stem 193 of the filter head 161. The top endplate 169includes an inwardly directed radial lip 194 which is positioned betweenthe upper end 195 of the flow nozzle 180 and the inner lip portion 191.An innermost radial portion of radial lip 194 provides an abutmentsurface for lip portion 191. The foregoing description involving theinner seal 166, top endplate 169, and flow nozzle 180 is virtuallyidentical to the assembly and relationships of the correspondingcomponent parts of the FIG. 1 assembly.

With reference to FIG. 19, the structural details of the filter head 161are illustrated. A perspective view of the underside of the filter head161 is illustrated in FIG. 24. Filter head 161 includes an annular outerflange 197 which is constructed and arranged with an annular channel 198(inverted) which is sized, shaped, and positioned to fit over andreceive the outer seal 167 as well as a small portion of the outerhousing 162 and nutplate 163 as is illustrated in FIGS. 20 and 21. Theouter annular wall 199 is externally threaded around its lower edge 200for threaded engagement with the internal threads 201 of the nutplate163. The inner annular wall, (i.e., inner stem 193), is spaced apartfrom wall 199 and defines therewith an annular inlet flow corridor. Flowapertures 202 are provided in the upper wall 203 of the filter head 161in order for the fluid which is to be filtered to enter the fluid filter160.

Inner stem 193 includes a recessed, annular protrusion 192 which issubstantially concentric with the remainder of stem 193 and extends fromannular bearing surface 204 in the direction of the inner seal 166. Aswill be described in greater detail, the inner stem 193 is inserted intothe passageway 191a defined by the inner lip portion 191 of the innerseal such that protrusion 192 establishes a liquid-tight interfaceagainst lip portion 191. Passageway 191a and protrusion 192 are eachsubstantially cylindrical and are sized such that there is aninterference fit causing the rubber compound used for inner seal 166 tobe resiliently compressed in order to create the annular liquid-tightinterface. Bearing surface 204 is located radially outwardly of theprotrustion 192.

The axial positioning of the inner stem 193 is influenced by severalportions of the fluid filter 160 and by various dimensionalrelationships involving these portions. The extent of threadedengagement between the outer annular wall 199 and the internal threads201 of the nutplate is one factor. The abutment of bearing surface 204against the upper surface of the inner lip portion 191 is another factorwhich influences the axial relationship between the filter head 161 andfluid filter 160. The axial length of support spring 168 relative to theaxial length of the two filtering elements and the thickness of innerseal 166 are other factors. When the annular bearing surface 204 abutsagainst the top surface of lip portion 191, the fluid filter 160 is notfully seated and engaged into the filter head 161. The continued axialadvancement of the filter head onto the fluid filter, (i.e., threadedengagement), causes the bearing surface 204 to push against the lipportion 191 and in turn the support spring is compressed. The springconstant also has an effect on the ease or difficulty in the continuedthreaded advancement. Another factor which is involved in the axialrelationship between the filter head 161 and the fluid filter 160 is theengagement of the outer seal 167 into the inverted channel 198. Thepoint at which these two portions abut, relative to when the bearingsurface 204 abuts against the lip portion 191 relative to springcompression in the axial direction and relative to the thread engagementbetween the nutplate 163 and the filter head 161 all have an effect onthe ease or difficulty of installing the fluid filter 160 onto thefilter head 161 and the ease or difficulty in removing the fluid filterfrom the filter head.

With reference to FIGS. 22 and 23, the inner seal 166 is illustrated ingreater detail. Consistent with the objectives of the present invention,inner seal 166 includes annular inner lip portion 191 and threeequally-spaced flanges 208a-208c which are in unitary, moldedconstruction with lip portion 191. Before installation onto the filterhead 162, the spring 168 pushes up on the filtering elements 164 and 165causing the upper surface of each flange 208a-208c to abut up againstthe lower edge 190 of the nutplate 163. In this "before installation"condition, the flow passageways which are created between the inner sealand the nutplate and in between the three flanges 208a-208c provide ameans of drainage. It is the open area between adjacent flanges whichprovides the open area for the flow passageways. The minimal clearancesof these flow passageways, while adequate for drainage and venting, arenot adequate to handle the full flow requirements during vehicleoperation. When the fluid filter 160 is threaded onto the filter head161 and bearing surface 204 pushes down on the lip portion 191,additional clearance is created between the inner seal and the loweredge of the nutplate, thereby establishing a radial flow area for theincoming fluid which is delivered by way of the filter head. Thisadditional clearance is adequate to handle the full flow requirements.The inside edges of the lip portion 191 and the cylindrical openingdefined by the inner lip portion are designed substantially the same asthe corresponding portions of inner seal 29.

As generally described with regard to FIGS. 18-24, the assembly, (i.e.,installation), sequence between the filter head 161 and the fluid filter160 begins with thread alignment and then thread engagement. As thethreaded engagement between the filter 161 and the nutplate 163continues, the inner seal 166 is engaged, pushing down on the twofiltering elements 164 and 165 and axially compressing the supportspring 168. The support spring 168 acts as a thrust bearing and thedownward axial movement of the primary filtering element opens up theradial flow areas. Next, with only the friction of the threads and thespring to resist turning, the outer seal is contacted by the invertedchannel 198 of the filter head 161. This procedure allows for moreaccurate compression of the outer seal.

As will be understood, the ability of the present invention to functionin the manner described is dependent on the design of the filter headand the dimensional relationship between the bearing surface 204,protrusion 192, the external threads on annular wall 199, the base ofchannel 198, and the location of the lip portion 199 before installationof the fluid filter 160 onto the filter head 161. When the fluid filter160 is to be removed from the filter head 161, the installation sequenceis followed in the reverse order of the sequence which has beendescribed for installation.

With regard to FIGS. 25-31, a second arrangement of the relatedembodiment of the present invention is illustrated. The only differencebetween fluid filters 215 and 160 is limited to the differences betweenthe two corresponding inner seals 216 and 166. There is also adifference between the filter heads 217 and 161 which is necessary inorder to create a slightly different approach for the present invention.As for the remaining components, the outer seals, nutplates, filteringelements, outer housings, flow nozzles, and support springs arevirtually identical for fluid filters 160 and 215 and accordingly, thesame reference numerals have been used to denote that these componentsare virtually identical.

The differences between inner seal 166 and inner seal 216 is bestillustrated by a comparison of FIGS. 22 and 23 versus FIGS. 29 and 30.Inner seal 216 includes an annular inner lip portion 219 which defines asubstantially cylindrical inner opening 220 which is further defined byinner annular ribs 221 and 222 which are virtually identical to ribs 85and 86 (see FIG. 7) as well as the ribs on lip portion 191. Inner seal216 has a substantially flat upper surface 223 which is only slightlyrecessed below the upwardly protruding annular rib 224 which is part ofthe inner lip portion 219. Disposed in the annular upper surface 223 areten equally-spaced flow openings 228. Aligned with each flow opening 228is a corresponding radial flow channel 229 (ten total) located in theunderside surface of the inner seal 216. Each flow channel 229 has agenerally rectangular shape in lateral section and extends from theouter circumferential edge 230 radially inwardly until the flow channel229 intersects the corresponding flow opening 228.

With reference to FIG. 31, a perspective view of the filter head 217 isillustrated. Included as part of filter head 217, in addition to thevarious flow inlets and the flow outlet, are four equally-spacedprojections 231 which extend down from the lower edge 232 of theexternally threaded outer annular wall 233. Projections 231 areconstructed and arranged to contact the upper or top surface 223 ofinner seal 216 as the means of pushing the primary filtering element 164in a downward direction so as to axially compress support spring 168.This movement of the primary filtering element 164 also moves theby-pass filtering element 165 and establishes greater clearance betweenthe top surface 223 of the inner seal 216 and the lower edge of thenutplate. The installation sequence described for fluid filter 160 andfilter head 161 of FIGS. 18-24 is essentially the same for fluid filter215 and filter head 217 of FIGS. 25-31. The only substantive differencebetween these two sets of illustrations and the corresponding fluidfilters and filter heads is the use of protrusion 192 and bearingsurface 204 to push against the inner seal to move the primary filteringelement as compared to the use of the four projections 231. Theprotruding stem 236 of filter head 217 is still inserted into the inneropening 220 and is sized and shaped relative to inner seal 216 so thatannular ribs 221 and 222 contact the outside diameter of the protrudingstem with a liquid-tight fit so as to create a sealed interface at thatlocation.

The flow openings 228 in the inner seal 216 which connect to the flowchannels 229 in the lower (bottom) surface provide a drainage flow pathwhile maintaining a smooth surface for the head projections 231 to bearagainst during installation. The open spaces 237 which are positionedbetween each pair of adjacent projections 231 provide four radial flowpaths between the filter head 217 and the inner seal 216 afterinstallation (see FIGS. 27 and 28). Prior to fluid filter 215installation onto filter head 217, the minimal flow clearances providedbetween the nutplate 163 and the inner seal 216 by openings 228 andchannels 229 are adequate for drainage but not adequate to handle thefull flow requirements during vehicle operation. Additional clearanceareas which are adequate to handle the full flow requirements arecreated when the filter head pushes the inner seal away from thenutplate.

If the nutplate design of FIGS. 4 and 5 (nutplate 30) or the nutplate163 of either FIG. 18 or FIG. 25 (same basic design as nutplate 30) isused with a "solid" inner seal, such as inner seal 132, it is possibleto completely block off any radial flow between the top surface of theinner seal and the lower edge of the nutplate and thereby effectively"seal" the fluid filter. If in fact inner seal 132 is used, it isimportant for the circumferential line of contact between the lowerannular edge 73 of the nutplate 30 (or 163) to be against the uppersurface of the inner seal, either radially inwardly or radiallyoutwardly of the pockets 146. While pockets 146 do not perforate thethickness of inner seal 132, it would be possible for a flow path to becreated beneath edge 73 if the nutplate 30 is located so as tocircumferentially span the pockets 146. As an alternative, the pockets146 could be eliminated or in effect filled in so that the inner seal132 would be completely solid and provide a continuous and smooth andsubstantially flat top surface in order to make sealing contact with thelower edge of nutplate 30. This arrangement would create a sealedpackage which would even eliminate the minimal clearances as describedherein and designed for drainage.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

What is claimed is:
 1. A unitary nutplate for a fluid filter assemblyfor providing a mounting interface between an engine block mounting baseand the remainder of the fluid filter assembly, said fluid filterassembly being constructed and arranged to receive a flow of incomingoil to be filtered by a filtering element and to discharge said oildownstream of said filtering element, said unitary nutplate comprising:afirst annular wall portion constructed and arranged to be attached to anouter shell of the fluid filter assembly; a second annular wall portionconstructed and arranged to be located radially inwardly of said firstannular wall portion and axially spaced from said first annular wallportion, said second annular wall portion being internally threaded forthreadedly mounting onto an engine block mounting base; and aconnecting, annular wall portion positioned between said first annularwall portion and said second annular wall portion, said second annularwall portion including a lower edge and said flow of incoming oilflowing through a passageway which is defined in part by said loweredge, said first, second, and connecting annular wall portions beingfree of any flow passages therethrough.
 2. The unitary nutplate of claim1 wherein the radial distance of separation between an outer surface ofsaid first annular wall portion and an inner surface of said secondannular wall portion does not exceed 0.5 inches.
 3. The unitary nutplateof claim 2 wherein said second annular wall portion includes a pluralityof spacer tabs extending axially away from said first annular wallportion.
 4. The unitary nutplate of claim 3 wherein each spacer tab ofsaid plurality of spacer tabs having an inner surface which is threaded.5. The unitary nutplate of claim 4 wherein the internally threadedsecond annular wall portion and the threaded inner surface of eachspacer tab of said plurality of spacer tabs have the same thread pitch.6. The unitary nutplate of claim 1 wherein said second annular wallportion includes a plurality of spacer tabs extending axially away fromsaid first annular wall portion.
 7. The unitary nutplate of claim 6wherein each spacer tab of said plurality of spacer tabs having an innersurface which is threaded.
 8. The unitary nutplate of claim 7 whereinthe internally threaded second annular wall portion and the threadedinner surface of each spacer tab of said plurality of spacer tabs havethe same thread pitch.
 9. A nutplate for a fluid filter assembly forproviding a mounting interface between an engine block mounting base andthe remainder of the fluid filter assembly, said fluid filter assemblybeing constructed and arranged to receive a flow of incoming oilupstream of a filter element, said nutplate comprising:a sidewall whichdefines an interior opening, said sidewall being free of any flowpassageways therethrough and being constructed and arranged with a firstwall portion and a second wall portion, said first wall portionincluding an outer lip portion which is constructed and arranged to beattached to an outer shell of the fluid filter assembly said second wallportion being internally threaded and including a lower edge, said flowof incoming oil flowing through a passageway interior to said fluidfilter assembly which is defined in part by said lower edge.
 10. Thenutplate of claim 9 wherein said outer lip portion having an outersurface and said second wall portion having an inner surface which ispositioned radially inwardly of the outer surface of said outer lipportion.
 11. The nutplate of claim 10 wherein the radial distance ofseparation between the outer surface of said outer lip portion and theinner surface of said second wall portion does not exceed 0.5 inches.12. The nutplate of claim 11 wherein said second wall portion includes aplurality of spacer tabs extending axially away from said outer lipportion.
 13. The nutplate of claim 12 wherein each spacer tab of saidplurality of spacer tabs having an inner surface which is threaded. 14.The nutplate of claim 13 wherein the internally threaded second wallportion and the threaded inner surface of each spacer tab of saidplurality of spacer tabs have the same thread pitch.
 15. The nutplate ofclaim 9 wherein said second wall portion includes a plurality of spacertabs extending axially away from said outer lip portion.
 16. Thenutplate of claim 15 wherein each spacer tab of said plurality of spacertabs having an inner surface which is threaded.
 17. The nutplate ofclaim 16 wherein the internally threaded second wall portion and thethreaded inner surface of each spacer tab of said plurality of spacertabs have the same thread pitch.
 18. A nutplate for a fluid filterassembly for providing a mounting interface between an engine blockmounting base and the remainder of the fluid filter assembly, saidnutplate comprising:an annular sidewall which defines an interioropening, said annular sidewall being free of any flow passagewaystherethrough and including an outer lip portion which is constructed andarranged to be attached to an outer shell of the fluid filter assembly,said annular sidewall further including an internally-threaded innerwall portion, said outer lip portion having an outer surface and saidinner wall portion having an inner surface, the inner surface of saidinner wall portion having an inside diameter size, the outer surface ofsaid outer lip portion having an outside diameter size, said insidediameter size being at least 75% of said outside diameter size.
 19. Aunitary nutplate for a fluid filter assembly for providing a mountinginterface between an engine block mounting base and the remainder of thefluid filter assembly, said unitary nutplate comprising:an annularsidewall which defines an interior opening, said annular sidewall beingfree of any flow passageways and including an outer lip portion which isconstructed and arranged to be attached to an outer shell of the fluidfilter assembly, said annular sidewall further including aninternally-threaded inner wall portion, said outer lip portion having anouter surface and said inner wall portion having an outer surface whichis positioned radially inwardly of the outer surface of said outer lipportion, wherein the radial distance of separation between the outersurface of said outer lip portion and the inner surface of said innerwall portion does not exceed 0.5 inches and wherein said inner wallportion includes a lower edge and said unitary nutplate further includesa plurality of spacer tabs extending axially from said lower edge in adirection away from said outer lip portion.
 20. The unitary nutplate ofclaim 19 wherein each spacer tab of said plurality of spacer tabs havingan inner surface which is threaded.
 21. The unitary nutplate of claim 20wherein the internally threaded inner wall portion and the threadedinner surface of each spacer tab of said plurality of spacer tabs havethe same thread pitch.
 22. A unitary nutplate for a fluid filterassembly for providing a mounting interface between an engine blockmounting base and the remainder of the fluid filter assembly, saidunitary nutplate comprising:an annular sidewall which defines aninterior opening, said annular sidewall being free of any flowpassageways and including an outer lip portion which is constructed andarranged to be attached to an outer shell of the fluid filter assembly,said annular sidewall further including an internally-threaded innerwall portion, said outer lip portion having an outer surface and saidinner wall portion having an outer surface which is positioned radiallyinwardly of the outer surface of said outer lip portion, wherein saidinner wall portion includes a lower edge and said unitary nutplatefurther includes a plurality of spacer tabs extending axially from saidlower edge in a direction away from said outer lip portion.
 23. Theunitary nutplate of claim 22 wherein each spacer tab of said pluralityof spacer tabs having an inner surface which is threaded.
 24. Theunitary nutplate of claim 23 wherein the internally threaded inner wallportion and the threaded inner surface of each spacer tab of saidplurality of spacer tabs have the same thread pitch.
 25. A nutplate fora fluid filter assembly for providing a mounting interface between anengine block mounting base and the remainder of the fluid filterassembly, said nutplate comprising:a sidewall which defines an interioropening, said sidewall being free of any flow passageways therethroughand including an outer lip portion which is constructed and arranged tobe attached to an outer shell of the fluid filter assembly, saidsidewall further including an internally-threaded inner wall portionwhich is separated from said outer lip portion by two radiused bends,wherein the radial distance of separation between the outer surface ofsaid outer lip portion and the inner surface of said inner wall portiondoes not exceed 0.5 inches and wherein said inner wall portion includesa lower edge and said nutplate further includes a plurality of spacertabs extending axially from said lower edge in a direction away fromsaid outer lip portion.
 26. The nutplate of claim 25 wherein each spacertab of said plurality of spacer tabs having an inner surface which isthreaded.
 27. The nutplate of claim 26 wherein the internally threadedinner wall portion and the threaded inner surface of each spacer tab ofsaid plurality of spacer tabs have the same thread pitch.
 28. A nutplatefor a fluid filter assembly for providing a mounting interface betweenan engine block mounting base and the remainder of the fluid filterassembly, said nutplate comprising:a sidewall which defines an interioropening, said sidewall being free of any flow passageways therethroughand including an outer lip portion which is constructed and arranged tobe attached to an outer shell of the fluid filter assembly, saidsidewall further including an internally-threaded inner wall portionwhich is separated from said outer lip portion by two radiused bends,wherein said inner wall portion includes a lower edge and said unitarynutplate further includes a plurality of spacer tabs extending axiallyfrom said lower edge in a direction away from said outer lip portion.29. The nutplate of claim 28 wherein each spacer tab of said pluralityof spacer tabs having an inner surface which is threaded.
 30. Thenutplate of claim 29 wherein the internally threaded inner wall portionand the threaded inner surface of each spacer tab of said plurality ofspacer tabs have the same thread pitch.
 31. A nutplate for a fluidfilter assembly for providing a mounting interface between an engineblock mounting base and the remainder of the fluid filter assembly, saidnutplate comprising:an annular sidewall which defines an interioropening, said annular sidewall being free of any flow passagewaystherethrough and including an outer lip portion which is constructed andarranged to be attached to an outer shell of the fluid filter assembly,said annular sidewall further including an internally-threaded innerwall portion, said outer lip portion having an outer surface and saidinner wall portion having an inner surface, the inner surface of saidinner wall portion having an inside diameter size, the outer surface ofsaid outer lip portion having an outside diameter size, said insidediameter size being at least 75% of said outside diameter size, whereinsaid inner wall portion includes a lower edge and said unitary nutplatefurther includes a plurality of spacer tabs extending axially from saidlower edge in a direction away from said outer lip portion.
 32. Thenutplate of claim 31 wherein each spacer tab of said plurality of spacertabs having an inner surface which is threaded.